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sysfs: minimize heap allocations of sysfs paths
11a0918 ("nvme: allow to overwrite base sysfs path") added support for changing the sysfs path via an environment variable. Unfortunately, it added a heap allocation every time a sysfs path was requested. Modify the callers to not free the paths, which allows a string constant to be returned if the path isn't overridden, avoiding an allocation. Cache the path in a static variable so that if it is overridden, the heap-allocated string only needs to be constructed once and afterwards can be reused. Create a file sysfs.c to consolidate this logic instead of spreading them across 3 files. Also introduce a helper to factor out the duplicated code. Fixes: 11a0918 ("nvme: allow to overwrite base sysfs path") Signed-off-by: Caleb Sander Mateos <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -6,68 +6,12 @@ | |
| * Authors: Keith Busch <[email protected]> | ||
| * Chaitanya Kulkarni <[email protected]> | ||
| */ | ||
| #include <stdlib.h> | ||
| #include <stdio.h> | ||
| #include <string.h> | ||
| #include <dirent.h> | ||
| #include <libgen.h> | ||
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| #include <sys/param.h> | ||
| #include <sys/stat.h> | ||
| #include <sys/types.h> | ||
| #include <fcntl.h> | ||
| #include <unistd.h> | ||
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| #include "filters.h" | ||
| #include "types.h" | ||
| #include "util.h" | ||
| #include "cleanup.h" | ||
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| #define PATH_SYSFS_NVME "/sys/class/nvme" | ||
| #define PATH_SYSFS_NVME_SUBSYSTEM "/sys/class/nvme-subsystem" | ||
| #define PATH_SYSFS_BLOCK "/sys/block" | ||
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| char *nvme_ctrl_sysfs_dir(void) | ||
| { | ||
| char *basepath = getenv("LIBNVME_SYSFS_PATH"); | ||
| char *str; | ||
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| if (!basepath) | ||
| return strdup(PATH_SYSFS_NVME); | ||
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| if (!asprintf(&str, "%s" PATH_SYSFS_NVME, basepath)) | ||
| return NULL; | ||
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| return str; | ||
| } | ||
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| char *nvme_ns_sysfs_dir(void) | ||
| { | ||
| char *basepath = getenv("LIBNVME_SYSFS_PATH"); | ||
| char *str; | ||
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| if (!basepath) | ||
| return strdup(PATH_SYSFS_BLOCK); | ||
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| if (!asprintf(&str, "%s" PATH_SYSFS_BLOCK, basepath)) | ||
| return NULL; | ||
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| return str; | ||
| } | ||
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| char *nvme_subsys_sysfs_dir(void) | ||
| { | ||
| char *basepath = getenv("LIBNVME_SYSFS_PATH"); | ||
| char *str; | ||
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| if (!basepath) | ||
| return strdup(PATH_SYSFS_NVME_SUBSYSTEM); | ||
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| if (!asprintf(&str, "%s" PATH_SYSFS_NVME_SUBSYSTEM, basepath)) | ||
| return NULL; | ||
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| return str; | ||
| } | ||
| #include "private.h" | ||
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| int nvme_namespace_filter(const struct dirent *d) | ||
| { | ||
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@@ -132,7 +76,7 @@ int nvme_subsys_filter(const struct dirent *d) | |
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| int nvme_scan_subsystems(struct dirent ***subsys) | ||
| { | ||
| _cleanup_free_ char *dir = nvme_subsys_sysfs_dir(); | ||
| const char *dir = nvme_subsys_sysfs_dir(); | ||
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| return scandir(dir, subsys, nvme_subsys_filter, alphasort); | ||
| } | ||
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@@ -145,7 +89,7 @@ int nvme_scan_subsystem_namespaces(nvme_subsystem_t s, struct dirent ***ns) | |
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| int nvme_scan_ctrls(struct dirent ***ctrls) | ||
| { | ||
| _cleanup_free_ char *dir = nvme_ctrl_sysfs_dir(); | ||
| const char *dir = nvme_ctrl_sysfs_dir(); | ||
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| return scandir(dir, ctrls, nvme_ctrls_filter, alphasort); | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,86 @@ | ||
| // SPDX-License-Identifier: LGPL-2.1-or-later | ||
| #include <stdio.h> | ||
| #include <stdlib.h> | ||
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| #include "private.h" | ||
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| #define PATH_UUID_IBM "/proc/device-tree/ibm,partition-uuid" | ||
| #define PATH_SYSFS_BLOCK "/sys/block" | ||
| #define PATH_SYSFS_SLOTS "/sys/bus/pci/slots" | ||
| #define PATH_SYSFS_NVME_SUBSYSTEM "/sys/class/nvme-subsystem" | ||
| #define PATH_SYSFS_NVME "/sys/class/nvme" | ||
| #define PATH_DMI_ENTRIES "/sys/firmware/dmi/entries" | ||
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| static const char *make_sysfs_dir(const char *path) | ||
| { | ||
| char *basepath = getenv("LIBNVME_SYSFS_PATH"); | ||
| char *str; | ||
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| if (!basepath) | ||
| return path; | ||
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| if (asprintf(&str, "%s%s", basepath, path) < 0) | ||
| return NULL; | ||
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| return str; | ||
| } | ||
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| const char *nvme_subsys_sysfs_dir(void) | ||
| { | ||
| static const char *str; | ||
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| if (str) | ||
| return str; | ||
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| return str = make_sysfs_dir(PATH_SYSFS_NVME_SUBSYSTEM); | ||
| } | ||
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| const char *nvme_ctrl_sysfs_dir(void) | ||
| { | ||
| static const char *str; | ||
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| if (str) | ||
| return str; | ||
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| return str = make_sysfs_dir(PATH_SYSFS_NVME); | ||
| } | ||
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| const char *nvme_ns_sysfs_dir(void) | ||
| { | ||
| static const char *str; | ||
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| if (str) | ||
| return str; | ||
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| return str = make_sysfs_dir(PATH_SYSFS_BLOCK); | ||
| } | ||
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| const char *nvme_slots_sysfs_dir(void) | ||
| { | ||
| static const char *str; | ||
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| if (str) | ||
| return str; | ||
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| return str = make_sysfs_dir(PATH_SYSFS_SLOTS); | ||
| } | ||
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| const char *nvme_uuid_ibm_filename(void) | ||
| { | ||
| static const char *str; | ||
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| if (str) | ||
| return str; | ||
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| return str = make_sysfs_dir(PATH_UUID_IBM); | ||
| } | ||
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| const char *nvme_dmi_entries_dir(void) | ||
| { | ||
| static const char *str; | ||
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| if (str) | ||
| return str; | ||
|
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| return str = make_sysfs_dir(PATH_DMI_ENTRIES); | ||
| } |
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